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POSSIBLE APPLICATIONS FOR SHIPPING CONTAINERS

Standard Shipping Containers

Shipping Containers are by their very nature ‘Standard’. The design is regulated by ISO (International Standards Organisation). Containers ‘standardised’ carriage of freight, starting from the 1950’s and really taking hold in the 1960’s, not least because of the Vietnam war.

But like almost everything that is standard, there are variations.

Container sizes are usually defined by the length (external dimensions) e.g. 20ft or 40ft. The second variant is the height, most commonly 8ft 6ins but with 9ft 6ins becoming more common. The width is generally 8ft but can also be 2.5m. Mixing of measurements between imperial feet and inches and metric is common when discussing containers.

Weight capacities are also standard but with some variations.

The information here is intended to give guidance which will help when considering one of the almost infinite applications for a standard shipping container.


External Dimensions

Length

Shipping Containers
Standard lengths of 20ft (6.09m) and 40ft (12.19m).
Variations include 45ft (13.72m), 30ft (9.14m) and 10ft (3.05m).

For storage and other non-shipping applications other sizes are created by cutting down larger containers to required size. Most common cut-down sizes are 8ft (2.44m), 12ft (3.66m), 16ft (4.88m), 24ft (7.32m) and 32ft (9.75m). There are many container modification companies who will make other sizes to order.

Height

The most common height of a shipping container is 8ft 6ins (2.59m) though 9ft 6ins (2.90m) high containers are becoming increasingly common. In the past 8ft high (2.44m) was very common and there are some containers 9ft (2.74m) available but these are rare.

Width

The standard width of a shipping container is 8ft (2.44m). To accommodate some types of pallet, particularly in Europe 2.5m wide containers are available though are less commonly available to buy on the second hand market.

Internal Dimensions

The sides of a shipping container are in nearly all cases, corrugated. The depth of the corrugation is usually 1inch (25mm), which means that 2inches (50mm) is lost from the external width dimension. The back (blank end) of a shipping container is also corrugated and the doors are around 2inches (50mm) thick meaning that approximately 3 inches (75mm) is lost from the length.

The main reduction from external to internal dimensions is with height. The floor of a standard shipping container has an underside clearance of approximately 6 inches (150mm) and the floor has a thickness of 27mm (1.1 inches). As the roof is corrugated another 1 inch (25mm) is lost resulting in an internal dimension of around 8 inches less than external – 7ft 10 inches (2.39m), though this can vary slightly either way.

Through the door height

Through the door height is further reduced because of the steel top rail above the door which is a part of the structural integrity of the container which is 4 inches (100mm) thus reducing the entrance height to 7ft 6ins (2.28m), though this can vary slightly either way.

Weights

There are three relevant weights of a shipping container, the Tare Weight, the Gross Weight and the Payload. These are painted onto the outside of the doors of a shipping container when it is in shipping service or before it has been repainted for another application.

  • The Tare Weight is the weight of the container without cargo or contents.
  • The Gross Weight is the weight of the container plus the maximum payload it can hold i.e. the maximum total weight of the container.
  • The Payload (or Net Weight) is the weight of the cargo or contents that a container can hold.

Typical Weights of Standard Shipping Containers
Length
10ft
20ft
40ft
Max Gross Weight
11,300kg
30,480kg*
30,400kg
 
24,910lbs
67,200lbs
67,200lbs
Tare Weight
1,300kg
2,170kg
3,750kg
 
2,870lbs
4,780lbs
8,270lbs
Payload (or Net Weight)
10,000kg
28,310kg
26,730kg
 
22,040lbs
62,420lbs
58,930lbs

*The most common alternative for 20fts is 24,000kg for stores manufactured to a lower specification.

Note that cut-down containers cannot hold the same weight when lifted as a standard container because the structure of the container has been altered. The container modification company should be able to supply details of capacities and advise if their design has been weight tested for lifting.


Cubic Capacity

Typical Cubic Capacities of Standard Shipping Containers
Length
10ft
20ft
40ft
Cubic Capacity
15.95 cu m
33.2 cu m
67.59 cu m
 
563.3 cu ft
1,170 cu ft
2,387 cu ft


Structure

Shipping containers are designed to carry cargo. They are designed to be lifted vertically from above by cranes and transferred from ship to shore and between other forms of transport such as trains and lorries. Therefore they need to have strength in the top corners where they are engaged by the twistlocks of a container lifting crane. The corner castings in the top corners of the container are therefore points of strength.

The strength is transferred down through the corner posts to the corner castings at the bottom and then through the floor. The floor is constructed of steel cross members approximately 6 inches (150mm) deep, which are approximately 20 inches (508mm) apart and give transverse strength and support the floor. The cross members are welded at each end to longitudinal beams which run the length of the container between the corner castings. This all means that the strength of a shipping container lies within the corner posts and the floor. Structural alterations or damage to these components will weaken the container.

Doors

The doors of a standard shipping container are double doors fitted into one end and hinged so as to maximise the size of the opening when both doors are open and swung back. The doors swing back on the hinges almost 270° and can be secured to the sides of the container. The doors are secured in the closed position by two locking locking bars on each door which rotate so that handles drop into keepers and the locking bars are secured by cams top and bottom. The doors are sealed all of the way around with rubber seal, which means that the container is sealed against external conditions.

Cut down containers are often fitted with doors manufactured to a lesser specificationThan original shipping container doors. The steel will often be of a lower gauge (thickness), the seals may be a lower specification, and there may be only one locking bar per door. It is also worth noting that because of the way they are fitted and the fact that the structural integrity of the container has changed these doors can never be as good as original doors though this is not to say that they are not fit for purpose e.g. for use as a store.

Container stores can also be fitted with fabricated single steel doors (or personnel doors). These can be fitted anywhere in the container that they are required. Although they do not provide the same width of access as double doors they can be very convenient and easier to open and close.

Whichever type of door is fitted the entrance to a container involves a step of about 8 inches (203mm). This needs to be borne in mind if wheeled access is required such as by forklift truck or for storage of a car. A ramp is generally required.

Materials

Contemporary shipping containers are manufactured to a very high standard utilising quality materials such as Corten Steel. The paint is also of a high quality and applied in factory conditions. Door components such as seals and locking bars are also quality. The container is designed for a life in a marine environment and is manufactured accordingly. This means that containers are generally over-specified for use as a store but it does mean that they have a very long life in this application.


For further information on shipping containers the following best-seller is recommended:
'The Box – How the Shipping Container Made the World Smaller and the World Economy Bigger’ by Marc Levison.


The information contained here is for guidance only. ContainerContainer do not accept any responsibility for any loss or damages resulting from use or interpretation of this information.